This single arm study will evaluate the efficacy, safety and tolerability of a new investigational protease inhibitor (PI) plus background antiretrovirals plus Fuzeon (90mg sc bid) in HIV-1 infected, triple-class treatment-experienced, Fuzeon-naive adults. The new investigational PI will be administered according to the procedures of the early access program in which the patient is enrolled. The anticipated time on study treatment is 3-12 months, and the target sample size is approximately 120 individuals.

Number of Participants With Any Adverse Event (AE) and Serious Adverse Event (SAE) [ Time Frame: Up to Week 28 ] [ Designated as safety issue: No ]

An AE is defined as any untoward medical occurrence in a participant or clinical investigation participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. SAEs are defined as those events that were fatal or immediately life-threatening, and those events that resulted in hospitalization; prolonged an existing hospitalization; resulted in disability; or was a congenital anomaly.

The participant was considered as virologic failure at Week 12 clinic visit if patient achieved HIV-RNA <50 copies/mL at Week 4, and HIV-RNA > 50 copies/mL at Week 12, and HIV-RNA >50 copies/mL confirmed at 2 to 4 weeks after Week 12 or if participants failed to achieve a viral load decrease from baseline greater or equal to 0.5 log10 at Week 12 and failed to achieve a viral load decrease from baseline greater or equal to 0.5 log10 confirmed at 2 to 4 weeks after Week 12. The participant was considered as virologic failure at Week 24 clinic visit if participant achieved HIV-RNA <50 copies/mL at week 12, and HIV-RNA >50 copies/mL at week 24/early discontinuation, and HIV-RNA >50 copies/mL confirmed at 2 to 4 weeks after week 24/early discontinuation or HIV-RNA >50 copies/mL at any time up to week 24 and HIV-RNA >50 copies/mL confirmed at 2 to 4 weeks after week 24/early discontinuation.

The participant was considered as virologic failure at Week 12 clinic visit if patient achieved HIV-RNA <50 copies/mL at Week 4, and HIV-RNA > 50 copies/mL at Week 12, and HIV-RNA >50 copies/mL confirmed at 2 to 4 weeks after Week 12 or if participants failed to achieve a viral load decrease from baseline greater or equal to 0.5 log10 at Week 12 and failed to achieve a viral load decrease from baseline greater or equal to 0.5 log10 confirmed at 2 to 4 weeks after Week 12. The participant was considered as virologic failure at Week 24 clinic visit if participant achieved HIV-RNA <50 copies/mL at week 12, and HIV-RNA >50 copies/mL at week 24/early discontinuation, and HIV-RNA >50 copies/mL confirmed at 2 to 4 weeks after week 24/early discontinuation or HIV-RNA >50 copies/mL at any time up to week 24 and HIV-RNA >50 copies/mL confirmed at 2 to 4 weeks after week 24/early discontinuation.

Number of Participants Adhering to Enfuvirtide (ENF) [ Time Frame: Weeks 4, 12, and 24 ] [ Designated as safety issue: No ]

Adherence to ENF treatment regimen was calculated using the participant's response to the query on the "Participant Adherence Questionnaire case report form (CRF)" about injections incomplete or missed in the last 4 days preceding the study visit. The percentage adherence to the ENF regimen at each study visit is given by: % Adherence = ([8 - the number of doses missed] / 8) x 100. The number and percentage of participants adhering to the ENF regimen were presented by adherence category (100%, ≥95%, ≥90% and ≥85%) at Weeks 4, 12, and 24.

Adherence to ENF treatment regimen was calculated using the participant's response to the query on the "Participant Adherence Questionnaire case report form (CRF)" about injections incomplete or missed in the last 4 days preceding the study visit. The percentage adherence to the ENF regimen at each study visit is given by: % Adherence = ([8 - the number of doses missed] / 8) x 100. The number and percentage of participants adhering to the ENF regimen were presented by adherence category (100%, ≥95%, ≥90% and ≥85%) at Weeks 4, 12, and 24.

Number of Participants With 1 or More Injection Site Reactions Meeting the Criteria of an Serious Adverse Event [ Time Frame: Week 1 to Week 24 ] [ Designated as safety issue: No ]

Injection site reactions (ISRs) referred to any localized sign or symptom, including erythema, induration, pruritus, nodules, ecchymosis (degree of bruising/ discoloration), and pain/discomfort. Injection site reactions were monitored by trained study personnel at weeks 1, 4, 12, 16, and 24. Interruption of ENF for toxicity management of recurrent local grade 3 or 4 ISRs until the sign or symptom resolved to grade 2 was at the discretion of the investigator. Any individual injection site signs or symptoms meeting the criteria for a serious adverse event (SAE) had to be reported as an SAE. In the event of a serious ISR, the participant was to immediately discontinue ENF and withdraw from the study. If the participant was not already hospitalized, serious ISRs required a clinic visit within 72 hours of the event.

Percentage of Participants With 1 or More Injection Site Reactions Meeting the Criteria of an Serious Adverse Event [ Time Frame: Week 1 to Week 24 ] [ Designated as safety issue: No ]

Injection site reactions (ISRs) referred to any localized sign or symptom, including erythema, induration, pruritus, nodules, ecchymosis (degree of bruising/ discoloration), and pain/discomfort. Injection site reactions were monitored by trained study personnel at weeks 1, 4, 12, 16, and 24. Interruption of ENF for toxicity management of recurrent local grade 3 or 4 ISRs until the sign or symptom resolved to grade 2 was at the discretion of the investigator. Any individual injection site signs or symptoms meeting the criteria for a serious adverse event (SAE) had to be reported as an SAE. In the event of a serious ISR, the participant was to immediately discontinue ENF and withdraw from the study. If the participant was not already hospitalized, serious ISRs required a clinic visit within 72 hours of the event.

Descriptive Summary of ISR Parameters (ie, Severity and Frequency of Pain and Symptoms) by Injection Device Based on an ISR Grading Tool. [ Time Frame: Week 24 ] [ Designated as safety issue: No ]

Injection site reactions (ISRs) referred to any localized sign or symptom, including erythema, induration, pruritus, nodules, ecchymosis (degree of bruising/ discoloration), and pain/discomfort. Injection site reactions were monitored by trained study personnel at weeks 1, 4, 12, 16, and 24. Grades 0 through 4 are a measure of intensity, not seriousness. Thus, a grade 3 or grade 4 sign or symptom could be severe, but not necessarily serious. Only active, ongoing ISR were counted. The maximum severity grade for pain/discomfort since the last visit at any injection site was recorded whether or not the maximum severity of pain/discomfort was ongoing at the time of clinical evaluation.

Number of Participants Discontinuing Study Medication Due to Clinical Adverse Events [ Time Frame: Up to Week 24 ] [ Designated as safety issue: No ]

The total number and percentage of participants who discontinued the study medication (ENF) due to clinical adverse events (including clinically significant laboratory abnormalities and AIDS Clinical Trials Group (ACTG) grade≥3 laboratory toxicities) were noted and presented.

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Please refer to this study by its ClinicalTrials.gov identifier: NCT00326963